Downhole drill for submarine drilling



R. W. SPEAR DOWNHOLE- DRILL FOR SUBMARINE DRILLING May 14, 1968 v v y Eiled March \ww/ m Mwy \y i M R. 2 m3 V W W H w R United States Patent 3,382,934 DOWNHOLE DRILL FOR SUBMARINE DRILLING 1 Richard W. Spear, Woodstock, Vt., assignor to Ingersoll- Rand Company, New York, N.Y., a corporation of New Jerse y Filed Mar. 3, 1966, Ser. No. 531,584

4 Claims. (Cl. 175-171) ABSTRACT OF THE DISCLOSURE Apparatus for drilling wherever a loose formation is likely to be encountered such as in submarine drilling. The apparatus provides a kerf drill bit rotatably connected to the drill casing and a primary percussive bit. The kerf bit drills a hole sufiiciently large to permit the casing to follow the bit down the hole. Impacts delivered to the percussive bit are transferred to the kerf bit.

This invention involves a novel apparatus for drilling wherever a loose formation such as sand or loose rock is likely to be encountered. One such place is in submarine drilling for widening or deepening harbors or rivers.

In prior methods of submarine drilling a casing is sunk into the muck on the bottom of a body of water. The drill and bit are then placed within the casing and the drilling of the rock is begun. When a hole has been drilled to the desired depth, the drill and bit are removed and a powder carton is lowered into the drilled hole; the casing is removed, and the powder carton is detonated.

One disadvantage of this method is that when the drill is removed, the loose rock and muck surrounding the hole is likely to, at least partially, fill the hole before the powder carton can be placed in the hole. The same problem is encountered if the drilling is being done in a formation covered by sand or other loose material.

This disadvantage has been overcome by drilling a hole large enough so that the casing will follow the bit down the hole. However, in prior apparatus, such as US. Patents Nos. 2,950,087 and 3,117,636, the casing must be rotated along with the bits. A large amount of energy is required to rotate the casing because it is deep in the earth. By this invention, the casing need not be rotated when the bits are rotated.

It is the principal object of this invention to provide apparatus for drilling a hole as large as the casing without rotating the casing.

It is another object of this invention to provide apparatus for drilling whereby the drilled hole is not filled with loose rock due to a cave-in prior to loading the hole with powder,

In general the above objects are carried out by providing apparatus for drilling comprising a casing, a secondary bit mounted on said casing for rotatable and slidable movement relative to said casing and having a keyed hole therein, a primary bit having a portion adapted to removably fit within said keyed hole; and means for delivering an impact to said primary bit, said primary bit being a percussive bit and having a radial shoulder about a portion thereof adapted to engage an upper portion of said secondary bit for transferring to said secondary bit an impact delivered to said primary bit.

With reference to the drawings:

FIG. 1 is a longitudinal section through the casing with the drill and inner bit in drilling position;

FIG. 2 is a bottom plan view of the device shown in FIG. 1; and

FIG. 3 is a longitudinal section through the casing with the inner bit removed.

"ice

In FIG. 1, there is shown the bed rock into which a hole is to be drilled for inserting a powder carton. Above the bed rock there may be loose material such as sand or water and muck. A casing 1 has a tubular member 2 attached to it by any suitable means such as weld 3. The casing is threaded at 4 at the lower end thereof.

A kerf bit generally indicated at 5 is provided with right-hand threads 6 around the upper portion thereof. Both the tubular member 2 and the kerf bit 5 are threaded only a few turns so that the kerf bit slidably and rotatably fits within the tubular member 2. The kerf or secondary bit 5 may slide axially a distance A as shown in FIG. 3, relative to the tubular member 2. The distance A is that distance between the screw threads on the kerf bit and tubular member when the flange 10 on the kerf bit abuts the lower end of the tubular member. The kerf bit 5 may also rotate relative to the tubular member and thus the casing 11. The number of threads on the tubular member and secondary bit can be limited to that number which is sufiicient to prevent the kerf or outer bit 5 from falling out of the tubular member when the assembly is lowered into or raised from the hole. The kerf bit has a square hole 7 with round corners 8 axially through it. The bore need not be square. It may have any number of keying surfaces or flat sides arranged so that primary bit 12 is in some way keyed to the secondary bit 5. This insures that when the primary or inner bit rotates, the secondary bit will also rotate.

An even number of tungsten carbide inserts 9 are circumferentially spaced around the kerf bit. As best shown in FIG. 1, the kerf bit has an outside diameter larger than that of the casing and tubular member. This allows the casing 1 to follow the bit down the hole 1-1, to rotate freely within the drilled hole and allows the cuttings from the kerf bit to be exhausted out the drilled hole.

A percussion or primary bit, generally indicated by the numeral 12, is adapted to fit within the square bore 7 in the kerf bit 5. At the lower end of the percussion bit, four tungsten carbide inserts 13 are spaced degrees apart as shown in FIG. 2. The upper portion of the percussion bit is provided with a radial shoulder 14 adapted to be in mating relation with the upper land 11 of the kerf bit 5. The land of the kerf bit is preferably at an angle of less than 90 degrees with respect to the longitudinal axes of the casing 1 and drill bits.

The shoulder 14 on the percussion bit 12 should be tapered so that when the percussion bit strikes the upper end of the kerf bit, the shoulder will not fracture.

The primary bit 12 has an axial bore :15 through which fluid passes to exhaust cuttings from the primary bit through the bore 16 and then up through the casing. The upper portion of the percussion or primary bit 12 is adapted to be attached to a drill generally indicated by 20 which is preferably a down-the-hole drill but may be any other type of drill or means for reciprocating and rotating the primary bit.

The tungsten carbide inserts 13 on the primary bit should be substantially the same size as the tungsten carbide inserts 9 on the kerf or secondary bit. This insures that during the drilling operation, each bit does an equal amount of work.

In operation, the kerf or secondary bit 5 is attached to the tubular member 2 by rotating one relative to the other until the two are free to slide and rotate relative to each 7 other. .The casing and kerf bit as shown in FIG. 3 are then lowered to the bed rock. The down-the-hole drill with the percussion or primary bit 5 attached is then lowered into the casing and the bit fits into the kerf bit as shown in FIGS. 1 and 2. A hole is then bored into the rock by a conventional method. The primary bit is repetitively struck by percussive means and rotated. When the primary bit is struck, a force is delivered to the secondary bit which thus acts as a percussion bit. Because of the keyed hole in the kerf bit, when the primary bit is rotated, the kerf bit will also be rotated. Because the kerf bit 5 rotates relative to the tubular member and casing, the casing will not rotate. The casing follows the two bits down the hole. This process continues until the hole is bored to the desired depth. The drill and primary bit are removed from the casing. Powder cartons are then lowered into the casing; the casing and kerf bit are removed, and the powder cartons are detonated.

Drilling often must be done in rock formations which are broken and loose. In prior methods of drilling, when the drill is removed, it often disturbs the loose rock causing it to cave and the powder is difficult to load. With my new apparatus for drilling, the casing remains in the hole until the powder has been loaded. This prevents a cave-in and allows easy loading of powder. The casing is not rotated so more energy can be used in drilling and not wasted on rotating the casing.

The above description merely illustrates a preferred embodiment of the invention, but the invention is not intended to be limited in any way except by the appended claims.

I claim:

1. Apparatus for drilling comprising:

a casing;

a secondary bit mounted on said casing for rotatable and slidable movement relative to said casing and having a keyed hole therethrough;

a primary bit having a portion adapted to removably fit within said keyed hole; and

means for delivering an impact to said primary bit;

said primary bit being a percussive bit and having a radial shoulder about a portion thereof adapted to engage an upper portion of said secondary bit for transferring to said secondary bit an impact delivered to said primary bit.

2. Apparatus according to claim 1 wherein the secondary bit is a kerf bit, and said primary bit and said secondary bit have carbide inserts in the lower portion thereof, said carbide portions being substantially equal 111 size.

3. Apparatus according to claim 2 where said primary bit has an axial bore through which fluid passes to exhaust cuttings.

4. Apparatus according to claim 1 wherein said means for delivering an impact to said primary bit is attached to the primary bit and fits within the casing.

References Cited UNITED STATES PATENTS 1,869,892 8/1932 Grove 175-257 X 2,675,213 4/1954 Poole 175257 X 3,227,230 1/1966 Lagerstrom l257 X CHARLES E. OCONNELL, Primary Examiner.

N. C. BYERS, .TR., Examiner. 

